An example of the above-stated type of power supply apparatus is disclosed in Japanese Patent No. 4758234 B. The power supply apparatus of Japanese Patent No. 4758234 B is arranged to be supplied with a selected one of commercial AC voltages of, for example, 200 V and 400 V. The power supply apparatus includes two inverters. When the voltage of larger value, 400 V, is supplied to the power supply apparatus, a DC voltage resulting from conversion of the supplied 400 V AC voltage is applied to a series connection of the two inverters, and, when the voltage of smaller value, 200 V, is supplied, a DC voltage resulting from conversion of the supplied 200 V AC voltage is applied to a parallel connection of the two inverters. Like this, depending on the magnitude of the voltage supplied to the power supply apparatus, the two inverters are connected in an appropriate one of series and parallel connections.